Influence of selected inorganic counter-ions on the structure and antimicrobial properties of silver(i) complexes with imidazole-containing ligands

Abstract

Water-soluble silver(I) complexes containing the 4(5)-(hydroxymethyl)imidazole ligand with the formula [Ag(4-CH₂OHimH)₂]X (where X = NO₃⁻, ClO₄⁻, CF₃COO⁻, BF₄⁻ and SO₃CH₃⁻) were synthesized. The complexes were characterized by NMR (¹H and ¹³C) and IR spectroscopy, ESI-MS spectrometry and EA. The molecular structures of three complexes were confirmed by X-ray crystallography. The antimicrobial activity of the silver(I) complexes were evaluated against six strains of microorganisms: Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa, Proteus hauseri and Candida albicans. All tested silver complexes displayed excellent antibacterial properties against Gram-positive bacteria. Among them, the complex containing the trifluoroacetate counter-ion exhibited the highest antibacterial activity, with MIC values 2 to 3-fold lower than that required by silver sulfadiazine.